Orientation change event bound in inject.js doesn't work for multiple blockly workspaces on one page.

[picklesrus]

The resize function uses getMainWorkspace which will only resize the most recently touched workspace.
See https://github.com/google/blockly/blob/master/core/inject.js#L325

[rachel-fenichel]

The culprit code is in inject.ts:

    // Some iPad versions don't fire resize after portrait to landscape change.
    if (userAgent.IPAD) {
      browserEvents.conditionalBind(
          window, 'orientationchange', document, function() {
            // TODO (#397): Fix for multiple Blockly workspaces.
            common.svgResize(common.getMainWorkspace() as WorkspaceSvg);
          });
    }

We should check whether this is still necessary for iPads. For other devices this code path isn't hit, and the resize handler in inject.ts is bound separately on each workspace.